The kinetics and mechanism of solubilization of human erythrocyte membranes by aqueous taurocholic acid and by non-ionic detergents will be determined using a light scattering-stopped flow technique. The same experimental apparatus will be used to study the mechanism of transport of nonelectrolytes such as urea across intact red cell membranes. Pre-treatment of the membranes with various enzymes and other reagents will be used to identify the probable location of pores for nonelectrolyte transport. Further work will also be done on red cell reflection coefficients for several mammalian species.